Other mistake: In one of the first scenes in the study, Mr. Boddy hands each guest a weapon and then proceeds to turn out the lights. The room is thrown into complete darkness. Unfortunately, there is a roaring fire in the fireplace that would have illuminated the room enough for everyone to see what was going on.

Deliberate mistake: The same footage of Ms. Scarlet screaming when the cook falls out of the freezer is used when Wadsworth falls out of the freezer. (Note the cigarette.)

Visible crew/equipment: Towards the end of the film, when the butler is explaining 'whodunit', as he stands at the front door, quite clearly at the top of the screen a microphone can be seen following him back and forth.

Audio problem: When they are putting the Cook's body on the sofa, Wadsworth walks by in the background and says "Careful, don't get blood on the sofa" however his mouth doesn't move.

Revealing mistake: After they find Mr. Boddy's body in the bathroom, Wadsworth starts shouting. A candlestick then falls and hits him on the head. Look at the candlestick when it falls: you can tell it was pulled by a string or something.

Factual error: When the evangelist first enters the mansion, Mrs. Peacock calls him a beatnik. However, the movie is set in 1954, and the word "beatnik" was not coined until 1958.

Continuity mistake: When the Armageddon guy comes to the door, Mrs. Peacock slams the door in his face, and the flier he was holding flutters out of his hand and lands on the floor. In the next shot, the flier disappears.

Continuity mistake: When everyone is in the Library, you can see the matches in a cup on the left of the fireplace. When Professor Plum says, "Wait a minute, suppose that one of us is the murderer," you can also see that the matches are in a "V" shape. When Wadsworth walks towards them to pull the matches out, most of them are all leaning to the left side of the cup. As the movie goes on, when the cop gets locked up in the Library for the second time, the same amount of matches are in the holding cup as if Wadsworth did not pull them out and they are in a straight line. (Third time code 1:02:40).

Audio problem: After the lights were shut off, when Yvette is running down the stairs, you can still hear Mrs. White screaming about the window upstairs. If the the third ending is true, then how could she have gotten to the Library before Yvette?

Other mistake: In the end, it was revealed Mrs. White turned off the power. However, when the power got turned off, you can see to the left of the screen, it is a male person's wrist turning off the electricity.

Other mistake: In third explanation, it shows a flashback of Mrs. White killing Yvette. If you look at the end of the rope you can see part of the rope is holding itself up. In reality it should have been hanging free.

Revealing mistake: When the cook's body is lowered to the kitchen floor, you can see her move her outstretched arm closer to her head.

Other mistake: When Mrs. White enters the house, she takes off a black and white cape so she now is wearing a light coat over her dress. There is a point at which she is about to take off the coat, and with the camera angle change, she has it in her hand.

Other mistake: In the study, when Wadsworth says that Mr. Boddy is the one that's blackmailing everyone, Colonel Mustard and Mr. Boddy get in a fight. Mr. Boddy pokes Colonel Mustard in the eyes. You can tell that he stops his fingers right in front of Mustard's eyes. Less than a second later, Colonel Mustard falls over.

Revealing mistake: In the hallway, the camera pulls back from the dining room towards the front door. The camera pulls back too far, and on the floor masking tape and a different type of wood can be seen, indicating where the set stops.